Most current purification methodologies are very expensive due to the requirement for multiple steps and empirical development. In principle, immuno-affinity chromatography (IAC) should provide a very attractive alternative as it affords remarkable enrichment in a single step and is easily adapted to any target compound. Unfortunately however, IAC has seen rather restricted use due to difficulty eluting captured ligand without inactivating the antibody and/or product. Generally a large number of candidate antibodies must be screened to find one that releases the antigen under sufficiently mild conditions. Even then, elution usually causes some antibody inactivation, making IAC operationally expensive due to the need for periodic column replacement. The proposed research will test efficacy of a molecular design capable of imposing allosteric regulation on any scFv. Elution conditions of IAC utilizing this technology are truly mild as allosteric regulator binding causes the scFv to adopt a low activity conformation that is readily accessible through flexibility inherent in its specialized structure. Consequently, no scFv unfolding occurs and full activity should be retained over numerous chromatography cycles. Furthermore, efficacy of the design is expected to facilitate utilization of even very high affinity scFv (eg. 10-11 M) in IAC. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE